Light source alignment device

ABSTRACT

A device in which an apertured, substantially cylindrical light source is aligned relative to the support thereof for providing a substantially optimum illumination profile therefrom. The foregoing abstract is neither intended to define the invention disclosed in the specification, nor is it intended to be limiting as to the scope of the invention in any way.

[451 July 16, 1974 LIGHT SOURCE ALIGNMENT DEVICE [75] Inventor: Wayne L. Kidd, Fairport, NY.

[73] Assignee: Xerox Corporation, Stamford,

Conn.

22 Filed: Dec. 7, 1972 21 Appl. No.: 313,024

[52] US. Cl 355/67, 240/4426, 33/180 R [51] Int. CI. G03b 27/54 [58] Field of Search 355/67; 240/442, 44.26; 33/180, 181

[56] References Cited UNITED STATES PATENTS 1,356,656 10/1920 Pearson 33/181 X Primary ExaminerRichard M. Sheen Attorney, Agent, or FirmH. Fleischer; .l. J. Ralabate; C. A. Green 57 ABSTRACT A device in which an apertured, substantially cylindrical light source is aligned relative to the support thereof for providing a substantially optimum illumination profile therefrom.

The foregoing abstract is neither intended to define the invention disclosed in the specification, nor is it intended to be limiting as to the scope of the invention in any way.

4 Claims, 3 Drawing Figures PATENTEDJUHBW 3.824.013-

SHEET 2 BF 2 1 LIGHT SOURCE ALIGNMENT DEVICE BACKGROUND OF THE INVENTION This invention relates generally to an electrophotographic printing machine, and more particularly concerns a device for aligning therein an apertured substantially cylindrical light source.

In a typical electrophotographic printing machine, a photoconductive surface is uniformly charged and exposed to a light image of an original document. Exposure of the photoconductive surface is generally obtained by reflecting light rays from the original document onto the photoconductive surface. The reflected light rays discharge the irradiated portions of the photoconductive surface recording thereon an electrostatic latent image corresponding to the original document. Generally, the electrostatic latent image is rendered visible by depositing toner particles on the photoconductive surface. The toner particles adhere electrostatically to the photoconductive surface in image configuration. Subsequently, the toner powder image is transferred from the photoconductive surface to a sheet of support material which may be plain paper or a transparent thermal plastic material, amongst others. A fuser fixes the toner powder image deposited on the sheet of support material to provide a permanent copy of the original document. The foregoing process is more fully described in U.S. Pat. No. 2,297,691 issued to Carlson in 1942.

Multi-colored copies may be produced by an electrophotographic printing machine in substantially the same manner as heretofore discussed. However, rather than forming a total light image of the original document, the light image is filtered producing a single color light image which is a partial light image of the original document. The single color light image exposes the charged photoconductive surface recording thereon a single color electrostatic latent image. Toner particles, of a color complementary to the color of the filtered light image, are deposited on the photoconductive surface to develop the electrostatic latent image recorded thereon. Thereafter, the single color toner powder image is transferred from the photoconductive surface to the support material. The foregoing sequence of events is repeated a plurality of cycles with differently colored light images and corresponding toner particles of a complementary color. Successive, individual single color toner powder images are transferred to the support material in superimposed registration with one another forming a composite multi-color powder image thereon. This multi-color powder image is then coalesced to the support material forming a multi-color co y.

l iiasmuch as the exposure mechanism utilized as a light source is an apertured fluorescent lamp, it is evident that the angular orientation of the aperture therein is critical to properly illuminate the original document. The angle of incidence between the light rays emitted from the apertured lamp and the original document should be optimized to provide an adequate illumination profile. Not only must the aperture of the cylindrical light source be appropriately aligned when the machine is manufactured and initially installed in the customers facility, but subsequent lamps replacing inoperative lamps must also be aligned therein. It is, therefore, evident that it is highly desirable to readily align the aperture of the lamp at a predetermined angular orientation relative to the original document. The alignment technique utilized should be repeatable and easily usable for replacement of lamps in the field, as well as installation of new lamps at the manufacturing facility.

Heretofore, various techniques have been utilized to appropriately orient apertured lamps relative to the original document. One such approach relies on sockets in the printing machine having appropriate key ways therein adapted to mate with keys on the lamp connectors. However, this approach increases the cost of the lamp and the socket disposed in the machine. Alternately, the lamp may include a substantially cylindrical connector adapted to mate with a substantially cylindrical socket. However, this type of socket and connector arrangement requires the alignment of the apertured lamp relative to the original document after the installation thereof. Hereinbefore, this has been achieved by rotating the lamp to approximately align manually the aperture therein to a preferred orientation. This technique frequently produces substantial misalignments resulting in uncontrolled illumination profiles and poor copy quality.

Accordingly, it is a primary object of the present invention to improve the alignment of an apertured light source relative to the support thereof for optimizing the illumination profile therefrom.

SUMMARY OF THE lNVENTlON Briefly stated, and in accordance with the present invention there is provided a device for aligning an apertured substantially cylindrical light source in the support thereof to provide a substantially optimum illumination profile therefrom.

Pursuant to the present invention, the device includes an elongated plate having a reference surface adapted to be located on a complementary surface in the light source support. A yoke, in the form of an arcuate portion extending into the plate from a surface substantially normal to the reference surface, is arranged to encompass a portion of the circumferential surface of the light source. In addition thereto, a calibration mark is disposed on the arcuate portion of the yoke. During alignment, the elongated plate is disposed with the reference surface thereof positioned on the complernentary surface of the light source support, the yoke being arranged to encompass the light source. In this way, the light source may be rotated to align one edge of the aperture thereof with the calibration mark located on the arcuate portion of the yoke to substantially optimize the illumination profile therefrom.

BRIEF DESCRIPTION OF THE DRAWlNGS Other objects and advantages of the present invention will become apparent upon reading the following detailed descriptionand upon reference to the drawings, in which:

FIG. 1 is a schematic perspective view of an electrophotographic printing machine incorporating therein an apertured light source requiring angular alignment;

FIG. 2 is a schematic illustration depicting the light source of the FIG. 1 printing machine being aligned by the device of the present invention; and

FIG. 3 is a perspective view of the device of the present invention for aligning the FIG. 2 light source.

While the present invention will be described in connection with a preferred embodiment, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary it is intended to cover all alternatives, modifications and equivalents as may be included within the spirit andscope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION For a general understanding of the disclosed electrophotographic printing machine having a substantially cylindrical apertured light source requiring alignment therein, continued reference is had to the drawings wherein like reference numerals have been used throughout to designate like elements. FIG. 1 schematically illustrates the various components of an electrophotographic printing machine for producing multicolor copies from a colored original. Although the light source alignment device of the present invention is particularly well adapted for use in an electrophotographic printing machine, it should become evident from the following discussion that it is equally well suited for use with a wide variety of light sources, and is not necessarily limited in its application to the particular embodiment shown herein.

. The printing machine depicted in FIG. 1 employs a photoconductive member having 'a rotatably mounted drum with a photoconductive surface 12 thereon. a Drum 10 is mounted on a shaft (not shown) journaled in the printing machine to rotate in the direction of arrow 14. In this way, drum 10 moves photoconductive surface 12 sequentially through processing stations A through E, inclusive. The various machine operating mechanisms'and drum '10 are driven at a predetermined speed relative to one another from a common drive motor (not shown). Hence, the machine-operations are coordinated to produce the proper sequencing of events at the processing stations.

Drum 10 initially moves photoconductive surface 12 through charging station A. Charging station A has positioned thereat a corona generating device, indicated generally at 16. Corona generating device 16 extends in a generally transverse direction across photoconductive surface 12. Preferably, corona generating device 16 is adapted to charge photoconductive surface 12 to a relatively high substantially uniform potential. U.S. Pat. No. 2,778,946 issued to Mayo in 1957 discloses a typical corona generating device which may be suitable for use in a multi-color electrophotographic printing machine.

Drum 10 rotates the charged photoconductive sur face 12 to exposure station B. At exposure station B, a color filtered light image of the original document is projected onto photoconductive surface 12. Exposure station E includes a moving lens system, generally designated by the reference numeral 18, and a color filter mechanism shown generally at 20. A suitable moving lens system is disclosed in U.S. Pat. No. 3,062,108 issued to Mayo in I962. As shown in FIG. 1, an original document 22, such as a sheet of paper, book, or the like, is placed face down upon transparent viewing platen 24. The lamp assembly, indicated generally at 25, includes a pair of lamps 26 associated with lens system l8. Lamp asser'nbly25 and lens system 18 are moved in a timed relation with drum 10 to scan successive incremental areas of original document 22 disposed upon platen 24. This produces a flowing light image of original document 22 which'is projected onto photoconductive surface 12. During exposure, a filter mechanism 20 interposes selected color filters into the optical light path of lens 18. The color filter operates on the light rays passing through lens 18 to record an electrostatic latent image on photoconductive surface 12 corresponding to a preselected spectral region of the electromagnetic wave spectrum, hereinafter referred to as a single color electrostatic latent image.

Drum 10 next rotates the single color electrostatic latent image recorded on photoconductive surface 12 to development station C. Development station C includes thereat threeindividual developer units, generally indicated by the reference numerals 28, 30 and 32, respectively. A suitable development station employing a plurality of developer units, is disclosed in copending application Ser. No. 255,259 filed in 1972. As disclosedin the foregoing patent application, developer units 28, 30 and 32 are all magnetic brush development systems. A typical magneticbrush developer unit utilizes a magnetizable developer mix including carrier granules and toner particles. The developer mix is brought continually through a directional flux field to form a brush thereof. Development is achieved by bringing the single color electrostatic latent image recorded on photoconductive surface 12 into contact with the brush of developer mix. Each of the respective developer units contain discretely colored toner particles corresponding to the complement of the spectral region of the wave length of light transmitted through filter mechanism 20, eg a green filtered electrostatic latent image is made visible by depositing green absorbing magenta toner particles thereon, blue and red latent images are developedwith yellow and cyan toner particles, respectively.

Thereafter, drum 10 is rotated to station D where the toner powder image adhering electrostatically to the latent image recorded on photoconductive surface 12 is transferred to a sheet of final support material 34. Sheet 34 may be, amongst others plain paper or a sheet of thermoplastic material. A bias transfer roll, shown generally at 36, recirculates sheet 34 in the direction of arrow 38. Roll 36 is electrically biased by a-potential of sufficient magnitude and polarity to attract electrostatically toner particles from photoconductive surface 12 to sheet 34. U.S. Pat. No. 3,612,677 issued to Langdon et al. in 1972 discloses a suitably electrically biased transfer roll. Transfer roll 36 is arranged to rotate in synchronism with photoconductive surface 12, i.e. transfer roll 36 and drum 10 rotates substantially at the same angular velocity. Inasmuch as sheet 34 is secured releasably on transfer roll 36 for movement in a recirculating path therewith, successive toner powder images may be transferred thereto in superimposed registration with one another. Thus, it is evident that successively colored toner particles are transferred from photoconductive surface 12 to sheet 34 in superimposed registration with one another to form a multi-colored toner powder image corresponding to the original document.

Referring once again to FIG. I, the sheet path for advancing sheet 34 to transfer roll 36 will hereinafter be described. A stack 40, of sheets 34 is supported on a tray 42 mounted pivotably in the printing machine frame. Tray 42 pivots in an upwardly direction so that the uppermost sheet 34 of stack 40 engages feed roll 44. Feed roll 44 is operatively associated with retard roll 46 to separate and advance successive uppermost sheets 34 from stack 40. Advancing sheet 34 moves into paper chute 48 and is directed into the nip of register rolls 50. Subsequently, gripper fingers 52, mounted on transfer roll 36, secure releasably thereto sheet 34 for subsequent movement therewith in a recirculating path.

After all of the discretely colored toner powder images have been transferred to sheet 34, gripper fingers 52 release sheet 34, and stripper bar 54 separates sheet 34 from transfer roll 36. After sheet 34 is stripped from transfer roll 36, it is moved on endless conveyor belt 56 to fixing station E, where a fuser indicated generally at 58, coalesces and permanently affixes the toner powder image to sheet 34. One type of suitable fusing apparatus is described in US. Pat. No. 3,498,592 issued to Moser et al. in 1970. After the fixing process, sheet 34 is advanced by endless belt conveyors 60 and 62 to catch tray 64 for subsequent removal therefrom by a machine operator.

Although a preponderance of the toner particles are transferred to sheet 34, invariably some residual toner particles remain on photoconductive surface 12 after the transfer of the powder image to sheet 34. The residual toner particles are removed from photoconductive surface 12 as drum moves through cleaning station F. Here the residual toner particles are first brought under the influence of a cleaning corona generating device (not shown) adapted to neutralize the electrostatic charge remaining on the toner particles. The neutralized toner particles are then mechanically cleaned from photoconductive surface 12 by a rotatably mounted brush 66. A suitable brush cleaning device is described in US. Pat. No. 3,590,412 issued to Gerbasi in 1971. Rotatably mounted brush 66 is positioned at cleaning station F and maintained in contact with photoconductive surface 12. In this manner, residual toner particles, remaining on photoconductive surface 12 after each transfer operation, are removed therefrom.

It is believed that the foregoing description is sufficient for purposes of the present application to illustrate the general operation of an electrophotographic printing machine embodying the teachings of the present invention.

Referring now to the specific subject matter of the present invention, FIG. 2 depicts a movable carriage 68 supporting a pair of light sources or lamps 26 therein. As depicted in FIG. 2, the alignment device of the present invention, indicated generally at 70, is positioned on movable carriage 68, and encompasses light source 26 to align it appropriately. Lamp carriage 68 is arranged to traverse platen 24 illuminating incremental widths of original 22. The exterior circumferential surface of lamp 26 is substantially opaque with a clear region or aperture 72 extending preferably over about a 45 arc. Aperture 72 extends preferably substantially along the entire length of cylindrically configured lamp 26. Preferably, lamp 26 operates at about 30 watts, 37 volts and l /6 amps rms, and includes three phosphors adapted to produce a red, green and blue output therefrom. Lamp 26 is adapted to be disposed in a mating socket (not shown) secured to movable carriage 68. The socket in which lamp 26 is electrically connected is adapted to permit lamp 26 to be mounted rotatably therein. Accordingly, lamp 26 may be rotated to align aperture 72 thereof relative to original document 22 disposed upon transparent viewing platen 24. The illumination profile depends substantially upon the angle of incidence between the light rays emitted from lamp 26 and document 22 disposed upon platen 24. To this end, alignment device 70 appropriately aids in the rotation of lamp 26 to provide the angular orientation of aperture 72 such that a substantially optimum illumination profile is generated therefrom.

Alignment device 70 includes, preferably, a substantially elongated plate 74 having a reference surface 76 adapted to be positioned upon a complementary surface 78 of movable carriage 68. In addition thereto, a yoke 80 has an arcuate portion 82 extending inwardly into plate 74 from surface 84 positioned substantially normal to reference surface 76. Arcuate portion 82, preferably, has a calibration mark 86 thereon. During alignment, lamp 26 is rotates so that one edge (in this case the top edge) of aperture 72 is substantially colinear with calibration mark 86. In this manner, aperture 72 is properly aligned to provide a substantially optimum illumination profile from lamp 26.

Turning now to FIG. 3, there is shown a perspective view of alignment device 70. As indicated therein, alignment device 70 includes an elongated plate 74. Elongated plate 74 is, preferably, rectangularly configured. A generally planar reference surface 76 thereon is adapted to mate with a complementary surface 78 on movable carriage 68. Yoke 80 has an arcuate portion 82 extending inwardly into plate 74 from surface 84. Surface 84 is substantially normal to reference surface 76. Calibration mark 86 is disposed on arcuate portion 82, preferably, about 205 from surface 84. Yoke 80 is disposed in the region of one end portion of plate 74. A generally planar, oblique surface 88 extends in a transverse direction from one end of reference surface 76 to one end of yoke 80. In addition to calibration mark 86, arcuate portion 82 is calibrated in a scale 90, preferably graduated in degrees. In this way, alignment device 70 may be utilized to orient lamp 26 to any preferred orientation, i.e. one edge of aperture 72 may be disposed adjacent any desired degree mark on calibration scale 90.

Preferably, arcuate portion 82 is of a size sufficient to encompass the circumferential surface of lamp 26 and arranged to extend over about a 90 arc. Oblique surface 88 is arranged to contact tangentially a portion of the circumferential surface of lamp 26 when reference surface 76 is disposed upon complementary surface 78 of movable carriage 68. By way of example, elongated plate 74 is preferably transparent and madefrom a plastic material, such as plexiglass.

In operation, alignment device 70 is disposed on movable carriage 68. Elongated plate 74 is disposed thereon such that yoke 80 has the arcuate portion 82 thereof surrounding a portion of the circumferential surface of lamp 26 with oblique surface 88 in contact tangentially therewith. Having positioned alignment device 70 appropriately about light source 26, light source 26 may now be rotated such that one edge of aperture 72 is aligned with calibration mark 86 on arcuate portion 82. Having achieved the foregoing preferred alignment, light source 26 will provide substantially optimum illumination of original document 22 positioned on transparent viewing platen 24 of the electrophotographic printing machine depicted in FIG. 1.

It is, therefore, evident that there has been provided in accordance with the present invention, an alignment device that fully satisfies the objects, aims and advantages set forth above. While this invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.

What is claimed is:

1. A device for aligning an illumination system employed in an electrophotographic printing machine of the type including an original document disposed on a transparent viewing platen, the illumination system having a movable support carriage with a first reference surface thereon and an apertured, substantially cylindrical light source mounted on the carriage, the carriage being arranged to move so that the light source illuminates incremental areas of the original document positioned on the viewing platen of the printing machine, said alignment device including:

an elongated plate comprising a second reference surface substantially complementary to the first reference surface of the carriage and a surface substantially normal to the second reference surface, said plate having an arcuate portion extending inwardly into said plate from the normal surface with an oblique surface extending substantially in a transverse direction from one end of the second reference surface to one end of the arcuate portion, and a calibration mark beingdisposed on the arcuate portion, said plate being mounted on the carriage with the second reference surface thereof contacting the first reference surface of the carriage and the arcuate portion arranged to encompass a portion of the circumferential surface of the light source with the oblique surface contacting tangentially a portion of the circumferential surface thereof so that the light source may be rotated to align one edge of the aperture thereof with the calibration mark providing a substantially optimum illumination profile therefrom.

2. A device as recited in claim 1, wherein said elongated plate is made preferably from a substantially transparent plastic material.

3. A device as recited in claim 2, wherein said elongated plate is preferably of a substantially rectangular configuration.

4. A device as recited in claim 3, wherein the arcuate portion of said plate includes a calibrated scale graduated preferably in degrees. 

1. A device for aligning an illumination system employed in an electrophotographic printing machine of the type including an original document disposed on a transparent viewing platen, the illumination system having a movable support carriage with a first reference surface thereon and an apertured, substantially cylindrical light source mounted on the carriage, the carriage being arranged to move so that the light source illuminates incremental areas of the original document positioned on the viewing platen of the printing machine, said alignment device including: an elongated plate comprising a second reference surface substantially complementary to the first reference surface of the carriage and a surface substantially normal to the second reference surface, said plate having an arcuate portion extending inwardly into said plate from the normal surface with an oblique surface extending substantially in a transverse direction from one end of the second reference surface to one end of the arcuate portion, and a calibration mark being disposed on the arcuate portion, said plate being mounted on the carriage with the second reference surface thereof contacting the first reference surface of the carriage and the arcuate portion arranged to encompass a portion of the circumferential surface of the light source with the oblique surface contacting tangentially a portion of the circumferential surface thereof so that the light source may be rotated to align one edge of the aperture thereof with the calibration mark providing a substantially optimum illumination profile therefrom.
 2. A device as recited in claim 1, wherein said elongated plate is made preferably from a substantially transparent plastic material.
 3. A device as recited in claim 2, wherein said elongated plate is preferably of a substantially rectangular configuration.
 4. A device as recited in claim 3, wherein the arcuate portion of said plate includes a calibrated scale graduated preferably in degrees. 